This invention relates generally to digital computer on-line data management systems and, more particularly, to a communication control unit for facilitating effective communication between multiple peripheral devices employing different communication disciplines and the system's main memory.
The term "communication (or line) discipline" may be defined as the set of rules or criteria governing the message format utilized by a particular peripheral device. Exemplary factors distinguishing one discipline from another involve, for example, synchronization, start and end of message sequence, message segment length, etc. Many different communication disciplines have evolved which are now well-known amongst those skilled in the art. The following list comprises only a small portion of those disciplines which might be of interest in a typical on-line data management system:
______________________________________ (1) VIP Visual Image Projection Terminal (Honeywell) (2) DN355 Datanet 355 (Honeywell) (3) Baudot TTY ITA Number Two Teletypewriter (4) ASCII TTY ASCII Teletypewriter - Odd or Even Parity (5) BISYC Point-to-Point Binary Synchronous Communications ______________________________________
Due to the lack of standardization amongst the various communication disciplines, it is generally necessary for a system to include separate communication controllers to accommodate each different discipline to be handled by the system. In some data management applications, it is not unusual for a system to have to accommodate six or more types of major network disciplines plus a multitude of other disciplines for specialized terminals and peripheral devices. To aggravate the problem further, new disciplines are continually being developed which, in turn, require that a new controller be designed, if an existing system capability is to be expanded to accommodate the new discipline.